This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We have applied MDM CARS microscopy to image atherosclerotic plaque lesions within the aortas of two atherosclerotic mouse models [unreadable]the ApoE-deficient mouse and the LDLR-deficient mouse. In this study, we aim to discriminate among different lipophilic components in the lesion, among which neutral lipid, cholesterol esters, and cholesterol. The microscopic distribution of these individual components, which correlate with plaque vulnerability, has remained hidden from view due to a lack of chemical selectivity. With hyper spectral CARS imaging, we hope to provide the chemical maps needed to bring the micro-environment of the lesion during disease progression in focus. CARS images along the full length of the aorta reveal differences in lipid structure and composition between the two atherosclerotic mouse models. Specifically, we observed several lipid-rich, needle- and plate-shaped structures within the plaque lesions of the ApoE-deficient mouse, which were significantly less prevalent in the LDLR-deficient mouse. Both models, however, did reveal similar macrophage-dense regions within the lesions, as well as comparable elastin fiber structure within the surrounding tissue. . We are currently performing multicomponent analysis on the retrieved spectra contained in the chemical maps to reveal the molecular origin of the spectroscopic signatures.